DSpace Collection:http://hdl.handle.net/2328/33312015-03-03T20:28:07Z2015-03-03T20:28:07ZThree dimensional reconstructed MRI of an acrylic
meniscal cartilage phantom: the effect of acquisition slice thickness upon accuracy of
volume measurementReynolds, Karen JaneKurmis, A PSlavotinek, John Paulhttp://hdl.handle.net/2328/100852013-05-13T01:37:45Z2004-01-01T00:00:00ZTitle: Three dimensional reconstructed MRI of an acrylic
meniscal cartilage phantom: the effect of acquisition slice thickness upon accuracy of
volume measurement
Authors: Reynolds, Karen Jane; Kurmis, A P; Slavotinek, John Paul2004-01-01T00:00:00ZA literature review of different pressure ulcer
models from 1942-2005 and the development of an ideal animal modelSmith, Anne-LouiseReynolds, Karen JaneNguyen, Phuong Kim Thihttp://hdl.handle.net/2328/97302013-05-13T01:37:28Z2008-01-01T00:00:00ZTitle: A literature review of different pressure ulcer
models from 1942-2005 and the development of an ideal animal model
Authors: Smith, Anne-Louise; Reynolds, Karen Jane; Nguyen, Phuong Kim Thi2008-01-01T00:00:00ZVessel calibre and haemoglobin effects on pulse oximetryMcEwen, MarkBull, GeoffReynolds, Karen Janehttp://hdl.handle.net/2328/72952013-05-13T01:29:25Z2009-01-01T00:00:00ZTitle: Vessel calibre and haemoglobin effects on pulse oximetry
Authors: McEwen, Mark; Bull, Geoff; Reynolds, Karen Jane
Abstract: Despite its success as a clinical monitoring tool, pulse oximetry may be improved with
respect to the need for empirical calibration and the reports of biases in readings associated
with peripheral vasoconstriction and haemoglobin concentration. To effect this
improvement, this work aims to improve the understanding of the photoplethysmography
signal - as used by pulse oximeters, and investigates the effect of vessel calibre and
haemoglobin concentration on pulse oximetry.
The digital temperature and the transmission of a wide spectrum of light through the fingers
of 57 people with known haemoglobin concentrations were measured, and simulations of the
transmission of that spectrum of light through finger models were performed.
Ratios of pulsatile attenuations of light as used in pulse oximetry were dependent upon
peripheral temperature and on blood haemoglobin concentration. In addition, both the
simulation and in vivo results showed that the pulsatile attenuation of light through fingers
was approximately proportional to the absorption coefficients of blood, only when the
absorption coefficients were small. These findings were explained in terms of discrete blood
vessels acting as barriers to light transmission through tissue.
Due to the influence of discrete blood vessels on light transmission, pulse oximeter outputs
tend to be dependent upon haemoglobin concentration and on the calibre of pulsing blood
vessels - which are affected by vasoconstriction/vasodilation. The effects of discrete blood
vessels may account for part of the difference between the Beer–Lambert pulse oximetry
model and empirical calibration.2009-01-01T00:00:00ZCorrelated Poincare indices for measuring heart rate variabilitySmith, Anne-LouiseReynolds, Karen JaneOwen, Harryhttp://hdl.handle.net/2328/33322013-05-13T01:26:18Z2007-12-01T00:00:00ZTitle: Correlated Poincare indices for measuring heart rate variability
Authors: Smith, Anne-Louise; Reynolds, Karen Jane; Owen, Harry
Abstract: Poincare indices are usually applied to HRV to summarise long data sets collected over 24 hrs. Many applications of HRV are interested in dynamic, short term changes (<1 min). This study uses Poincare indices published through the 1990's to the present, to determine which of them are correlated over the short term (25 beats). Dynamic changes were observed in 12 subjects preoperatively receiving fentanyl and midazolam sedation with ECG collected for 5 mins before and 5 mins after fentanyl administration. Poincare indices with a strong correlation (r>0.85) between the indices for each of the 12 subjects (p<0.001) (particularly with the common measures SDNN, RMSSD, pNN50 and meanRR) were identified. These indices will not be used for further investigation of dynamic effects of fentanyl and midazolam, two sedative drugs used in anaesthesia and intensive care. Indices that proved less suitable for short term analysis (eg, presence of outliers, inability to produce a valid index with smaller number of beats) were also identified. A shortlist of Poincare indices that do not correlate strongly with commonly used measures may prove interesting in determining dynamic characteristics of the effect of sedative drugs on autonomic nervous system activity.2007-12-01T00:00:00Z